1. Field of the Invention
The invention relates to a chemical vapor deposition process for growing epitaxial garnet crystals and complex metal oxide crystals other than garnet crystals by controlling the location of the reaction zone of the process.
2. Description of Prior Art
Techniques for obtaining magnetic oxide films on crystalline substrate include spraying suspension of reactants onto heated substrates, vacuum depositing metal alloys with subsequent oxidation, and chemically depositing on a substrate from mixed nitrate solutions followed by a firing of the material. More recently, EuO films have been prepared by electron beam evaporation and garnet films have been deposited by r-f sputtering.
Cech and Alessandrini by a paper entitled "Preparation of FeO, NiO, and CoO Crystals by Halide Decomposition," Trans. Am. Soc. Metals 50, 150, (1959), reported the epitaxial growth of certain materials by a chemical vapor deposition (CVD) method. Others independently extended the techniques reported and showed that complex metal oxides, specifically ferrites, could also be grown epitaxially by the CVD method. According to various publications, successful epitaxial growth techniques include CVD, r-f sputtering, and growth from molten solution (flux method).
At the present time, the emphasis in this field is on epitaxial films produced by the CVD method and on both epitaxial and polycrystalline films by the r-f sputtering method. However, the films grown by the CVD method, while exhibiting preferred characteristics, have been difficult to reproduce.
A CVD process is preferred in which the film deposited by the CVD method can be accurately and reliably reproduced. The present invention provides such a process.